Experimental study of high rayleigh number convection using cryogenic gaseous 4He

0352309 - ÚPT 2011 RIV CZ eng C - Conference Paper (international conference)
Urban, Pavel - Musilová, Věra - Skrbek, L.
Experimental study of high rayleigh number convection using cryogenic gaseous 4He.
Proceedings of the International Conference Experimental Fluid Mechanics 2010. Liberec: Technical University of Liberec, 2010 - (Vít, T.; Dančová, P.), s. 762-769. ISBN 978-80-7372-670-6.
[Experimental Fluid Mechanics 2010 -EFM10. Liberec (CZ), 24.11.2010-26.11.2010]
R&D Projects: GA AV ČR KJB200650902; GA ČR GA202/05/0218; GA MŠMT ED0017/01/01
Institutional research plan: CEZ:AV0Z20650511
Keywords : Rayleigh number * turbulent thermal convection * Kraichnan regime * convection
Subject RIV: BJ - Thermodynamics

Several laboratories worldwide try to elucidate the underlying mechanisms of turbulent thermal convection using cryogenic He gas, a working fluid with truly remarkable and widely tuneable properties. The focus is on the efficiency of the heat transfer, experimentally studied via the Nusselt (Nu) versus Rayleigh number (Ra) dependence, especially at very high Ra. In order to resolve existing controversies among published results, we designed and built a cryogenic apparatus capable of reaching Ra up to 2 × 10e15, thus covering the range of interest where various transitions such as that into the theoretically predicted ultimate Kraichnan regime have been claimed. The cylindrical convection cell of 300 mm both in diameter and height is designed to withstand pressures up to 250 kPa at working temperatures between 4.2 K and 12 K. The main advantage of this apparatus is minimized influence of its cell design and materials used on the studied convection. The first experimental results are resented.
Permanent Link: http://hdl.handle.net/11104/0191844